1. Field of the Invention
The present invention relates to a mobile phone for use in a radio communication system, and more particularly, to a mobile phone for selectively performing transmission/receipt diversity when radio frequency signals are transmitted and received.
2. Description of the Related Art
Communication between a mobile phone and a base station is well achieved in a strong electric field which provides good communication environments. However, in a weak electric field which provides poor communication environments, the communication between the mobile phone and the base station is not well achieved due to weak intensity of signals, thus requiring higher power consumption for reliable transmission and receipt of the signals. This results in higher power consumption of a battery of the mobile phone as well as increase of a signal-to-noise ratio. To overcome such a problem, a diversity technique of receiving radio frequency signals via various propagation paths has been suggested. Hereinafter, configuration of a conventional mobile phone to which the above-mentioned diversity technique is applied will be described with reference to FIG. 1.
Referring to FIG. 1, the conventional mobile phone includes an antenna 110 for transmitting and receiving radio frequency signals, a duplexer 120 coupled to the antenna 110 for transmitting/receiving the radio frequency signals to/from the antenna 110, a low noise amplifier 131 for amplifying intensity of the radio frequency signals received via the duplexer 120, a filter 132 for filtering the radio frequency signals amplified by the low noise amplifier 131 to remove noises from the radio frequency signals, a first receiving signal processor 133 for demodulating the radio frequency signals filtered by the filter 132 and converting the demodulated radio frequency signals into baseband signals to be output to a controller 140, a transmitting signal processor 151 for modulating the baseband signals transmitted from the controller 140 and converting the modulated baseband signals into radio frequency signals, a filter 152 for filtering the radio frequency signals output from the transmitting signal processor 151 to remove noises from the radio frequency signals, a power amplifier 153 for amplifying power of the radio frequency signals filtered by the filter 152, and a transmission/receipt isolator 154 for preventing a receiving signal received via the antenna 110 from being transmitted to the transmitting signal processor 151, and transmitting the radio frequency signal amplified by the power amplifier 153 to the duplexer 120.
In addition, the conventional mobile phone further includes an antenna 160 for receiving radio frequency signals, a band-pass filter 171 for filtering the radio frequency signals received from the antenna 160 to pass only radio frequency signals of a receipt band, a low noise amplifier 172 for amplifying intensity of the radio frequency signals filtered by the band-pass filter 171, a filter for filtering the radio frequency signals amplified by the low noise amplifier 172 to remove noises from the radio frequency signals, and a second receiving signal processor 174 for demodulating the radio frequency signals filtered by the filter 173 and converting the demodulated radio frequency signals into baseband signals to be output to the controller 140.
However, since the conventional mobile phone as configured above performs only receiving diversity, but does not perform transmission diversity, a base station can not correctly receive signals transmitted from the mobile phone in an area of poor communication environments, which may result in deterioration of quality of communication services provided to users of mobile phones. Particularly, since the conventional mobile phone can not control the receipt diversity according to ambient communication environments, and thus, must perform the receipt diversity even in the strong electric fields, wasteful power consumption of a battery of the mobile phone is unavoidable.